The present invention relates to a novel type of microwave antenna comprising an array of receiving elements each including a flat printed circuit structure on a dielectric support. It goes without saying that, due to the reciprocal character of an antenna, a receiving element or an antenna composed of a network of receiving elements is capable of operating as either an emitter (transmitter) or a receiver without modification of its characteristics. This remark remains valid without exception throughout the following description and the term "reception" can be always replaced by the term "emission" without departing from the scope of the invention.
In a large number of applications, and especially in the case of reception of television signals originating from satellites, it is important that the emission diagrams of the microwave antenna used correspond to the recommendations given by the C.C.I.R. (Comitee Consultatif International des Radiocommunications), which especially relate to the 3 dB-aperture and to the level of the side lobes. This correspondence can be obtained either by spacing adjacent receiving elements at distances which are smaller in the central zone of the antenna than in its peripheral zone, or by spacing all adjacent receiving elements at the same distance from each other while effecting a non-uniform amplitude distribution. However, the networks of non-equidistant sources have the disadvantage that it is a complex operation to position the supply networks because of the somewhat aleatoric arrangement adopted for the sources. When the number of non-equidistant receiving elements is large (which is absolutely necessary to ensure that the antenna has a sufficient gain), it becomes very difficult to position the supply network or networks, especially when parallel supply networks are used, which is due to the high density of the transmission lines of these networks and to the small space available for their placement.
The manufacture of such a very high frequency antenna is complex and expensive, especially in the case where it must receive television signals at 12 GHz with counterclockwise and clockwise rotational polarizations, because receiving elements must be coupled to two distinct supply networks.